It is usual that a packet-based wireless communication system includes a transmission unit and a reception unit and the transmission unit and the reception unit transmit and receive data between each other by using a packet. The transmission unit transmits a synchronization signal so that the start of a frame can be recognized. A sequence agreed by the transmission side and the reception side is used for the transmission of a synchronization signal. A preamble sequence and a Start Frame Delimiter (SFD) are used as the synchronization signal as described above. When data is transmitted and then received by using the synchronization signal, after bit synchronization is acquired by using a preamble sequence and a start time point of a frame is detected by using an SFD, the demodulation of the data is started.
FIG. 1 is a view illustrating the structure of an existing data transmission packet. In FIG. 1, a data transmission packet includes a preamble, SFD, a header, user data, and a Frame Check Sequence (FCS). Referring to FIG. 1, after a start time point of a frame is found by using the preamble and the SFD, user data is demodulated with reference to a demodulation parameter of the header. Parameters transmitted through the header include multiple pieces of information for seeking efficient use of transmission resources, such as information for supporting the transmission of a large amount of data in the case of a good channel environment, information for minimizing the amount of data transmission and ensuring reception gain in the case of a poor channel environment, etc.
However, in a wireless connection environment where there exist various systems including a 1:1 communication system, a communication system supporting an ad-hoc network, a communication system supporting 1 to multiple (1 to n) connections, etc., a communication system must support various packet lengths and various speeds of data transmission in order to have an efficient communication means, and successful demodulation of a header must be accomplished in order to succeed in transmitting and receiving user data of the communication system. In a system supporting various speeds of data transmission, because information on a transmission speed is provided through a header, a speed of transmission of a header must be fixed, and the highest reception performance must be maintained. Therefore, in order to successfully demodulate a header, a transmission speed must be fixed to the lowest transmission speed allowed by the relevant communication system.
It is natural that reception performance should be secured by causing a speed of transmission of a header to be the lowest speed in order to deliver packet demodulation information in a poor channel environment. However, when data is intended to be transmitted at a high speed in a good channel environment, a speed of transmission of a header fixed to the lowest speed, which corresponds to overhead, is a waste of transmission resources. For example, when a transmission speed of a communication system supports 62.5 kbps/125 kbps/500 kbps/1 Mbps, a speed of transmission of a header is fixed to 62.5 kbps. At this time, when communication is intended to be performed at a speed of 1 Mbps, due to a fixed speed of transmission of a header, the throughput of the communication system is reduced. Therefore, in the communication system supporting various speeds of data transmission, there is a need for a method for improving the throughput of the communication system without the occurrence of overhead even when the length of a packet is short.